A large aperture 4K day and night confocal fisheye lens

Abstract

The present application relates to a large aperture 4K day and night confocal fisheye lens, the optical system of the lens is composed of a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a diaphragm, a sixth lens, a seventh lens, an eighth lens and a ninth lens arranged in order from the object side to the image side along the optical axis; the diaphragm is arranged between the fifth lens and the sixth lens. Wherein the first lens, the second lens, the fourth lens and the ninth lens are glass spherical lenses, and the third lens, the fifth lens, the sixth lens, the seventh lens and the eighth lens are plastic aspherical lenses. Through the cooperation of the focal power of each lens, the surface type, the center thickness of each lens and the axial distance between each lens, the 4K ultra-high-definition imaging requirement of the fisheye lens is met, and the lens has the functions of large aperture, low temperature drift and day and night confocal.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of optical imaging technology, and particularly relates to a large-aperture 4K day and night confocal fisheye lens. BACKGROUND

[0002] The fisheye lens is a kind of super wide-angle optical lens, which has the characteristics of short focal length and large field of view, and the field of view angle thereof can reach 180 degrees, which is much larger than that of a conventional optical lens, and can be used for panoramic shooting without dead angle. Therefore, the fisheye lens has attracted more and more attention and has been widely used in scene monitoring, medical endoscopy, unmanned aerial vehicle shooting and engineering measurement fields.

[0003] In recent years, with the rapid development of the Internet of Things technology and image processing technology, the market has higher and higher requirements for the resolving power of the fisheye lens, and gradually pursues 4K ultra-high definition resolution pixels. However, most of the fisheye lenses on the market have pixels between 2 million and 6 million, which cannot meet the demand of 4K imaging. However, some fisheye lenses that can meet the demand of 4K imaging are difficult to meet the demand of large aperture, day and night confocal and low temperature drift at the same time. SUMMARY

[0004] In view of the deficiencies of the prior art, the technical problem to be solved by the present application is to provide a large-aperture 4K day and night confocal fisheye lens, which has the advantages of large aperture, 4K ultra-clear resolution, low temperature drift and day and night confocal.

[0005] In order to solve the above technical problems, the technical scheme of the present application is that the optical system of the lens is composed of a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a diaphragm, a seventh lens, an eighth lens and a ninth lens arranged in order from the object side to the image side along the optical axis.

[0006] Preferably, the first lens is a negative meniscus lens with negative focal power, the object side surface of which is convex, and the image side surface of which is concave; the second lens is a negative meniscus lens with negative focal power, the object side surface of which is convex, and the image side surface of which is concave; the third lens is a negative meniscus lens with negative focal power, the object side surface of which is convex, and the image side surface of which is concave; the fourth lens is a biconvex positive lens with positive focal power, both the object side surface and the image side surface of which are convex; the fifth lens is a lens with negative focal power, the object side surface of which is concave, and the image side surface of which is convex; the sixth lens is a biconvex positive lens with positive focal power, both the object side surface and the image side surface of which are convex; the seventh lens is a biconcave lens with negative focal power, both the object side surface and the image side surface of which are concave; the eighth lens is a biconvex positive lens with positive focal power, both the object side surface and the image side surface of which are convex; and the ninth lens is a biconvex positive lens with positive focal power, both the object side surface and the image side surface of which are convex; the first lens, the second lens, the fourth lens and the ninth lens are glass spherical lenses, and the third lens, the fifth lens, the sixth lens, the seventh lens and the eighth lens are plastic aspherical lenses.

[0007] Preferably, the focal length of the optical system is f, and the focal lengths of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens and the eighth lens are f1, f2, f3, f4, f5, f6, f7 and f8 respectively, wherein f1, f2, f3, f4, f5, f6, f7, f8 and f satisfy the following ratios: -10.0 < f1 / f < -9.0, -8.0 < f2 / f < -9.0, -3.0 < f3 / f < -2.0, 3.0 < f4 / f < 4.0, -8.0 < f5 / f < -7.0, 2 < f6 / f < 3.0, -3.0 < f7 / f < -2.0, 2.0 < f8 / f < 3.0, and 7.0 < f9 / f < 8.0.

[0008] Preferably, the first lens satisfies the relationship: 1.8 ≤ N d ≤ 2.0, V d ≤ 50.0; the second lens satisfies the relationship: 1.5 ≤ N d ≤ 1.8, V d ≥ 50.0; the third lens satisfies the relationship: 1.5 ≤ N d ≤ 1.8, V d ≥ 50.0; the fourth lens satisfies the relationship: 1.8 ≤ N d ≤ 2.0, V d ≤ 50.0; the fifth lens satisfies the relationship: 1.5 ≤ N d ≤ 1.8, V d ≤ 50.0; the sixth lens satisfies the relationship: 1.5 ≤ N d ≤ 1.8, V d ≥ 50.0; the seventh lens satisfies the relationship: 1.5 ≤ N d≤1.8, V d ≤50.0; the eighth lens satisfies the relationship: 1.5≤N d ≤1.8, V d ≥50.0; the ninth lens satisfies the relationship: 1.5≤N d ≤1.8, V d ≥50.0; wherein N d is the refractive index, V d is the Abbe number.

[0009] Preferably, the axial distance between each lens satisfies the following relationship, the air gap between the first lens and the second lens is: 3.5-4.0mm; the air gap between the second lens and the third lens is: 1.0-2.0mm; the air gap between the third lens and the fourth lens is: 2.0-3.0mm; the air gap between the fourth lens and the fifth lens is: 0.5-1.0mm; the air gap between the fifth lens and the diaphragm is: 0-0.1mm; the air gap between the diaphragm and the sixth lens is 0-0.5mm; the air gap between the sixth lens and the seventh lens is: 0-0.5mm; the air gap between the seventh lens and the eighth lens is: 0-0.5mm; the air gap between the eighth lens and the ninth lens is: 0-0.5mm.

[0010] Preferably, the third lens, the fifth lens, the sixth lens, the seventh lens and the eighth lens are all aspherical lenses; the aspherical curve equation expression is:

[0011]

[0012] Wherein, Z is the sagittal height of the aspherical surface at a height of h along the optical axis from the vertex of the aspherical surface; c is the paraxial curvature of the aspherical surface; k is the conic constant; α1, α2, α3, α4, α5, α6, α7, α8 are all high-order coefficients.

[0013] Preferably, the total optical length TTL of the optical system and the focal length f of the optical system satisfy: 16.0≤TTL / f≤18.0.

[0014] Preferably, the F number of the optical system is ≤2.1.

[0015] Preferably, the image height H of the optical system and the focal length f of the optical system satisfy: H / f≥3.5.

[0016] Preferably, the diaphragm of the optical system is located between the fifth lens and the sixth lens.

[0017] Preferably, the proximal side of the ninth lens is provided with a filter.

[0018] Compared with the prior art, the present application has the following beneficial effects:

[0019] 1. It adopts a glass-plastic hybrid optical system, consisting of only four glass spherical lenses and five plastic aspherical lenses, which reduces the cost of mass production of the lens while ensuring that the lens meets the imaging requirements of 4K ultra-high-definition resolution.

[0020] 2. Through the specific surface shape combination of the nine lenses and the reasonable distribution of optical power, the field of view of the lens reaches more than 187°, which can capture high-definition images of the scene in a wide range without blind spots, and achieve day and night confocal function.

[0021] 3. It has a large aperture and strong light transmission capability, with a relative illumination of over 55% at the edge of the field of view, ensuring that the lens has excellent image clarity and brightness in different lighting conditions.

[0022] 4. Multiple lenses with negatively correlated refractive index temperature coefficients are used to give the lens low temperature drift, achieving calorific value and ensuring that the lens can present high-resolution images under high or low temperature conditions.

[0023] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. Attached Figure Description

[0024] Fig. 1 This is a schematic diagram illustrating the structure of an embodiment of the present invention;

[0025] Fig. 2 This is a cross-axis chromatic aberration diagram of the entire working band of the invention embodiment;

[0026] Fig. 3 This is an axial chromatic aberration diagram of the entire working band of the invention embodiment;

[0027] Fig. 4 This is a field curvature distortion diagram of the entire operating band of the invention embodiment;

[0028] Fig. 5 This is a full-band MTF curve diagram of an embodiment of the invention.

[0029] In the diagram: STO - aperture stop; L1 - first lens; L2 - second lens; L3 - third lens; L4 - fourth lens; L5 - fifth lens; L6 - sixth lens; L7 - seventh lens; L8 - eighth lens; L9 - ninth lens; L10 - equivalent glass plate; IMA - imaging plane. Detailed Implementation

[0030] To make the above features and advantages of the present invention more apparent and understandable, specific embodiments are described below in conjunction with the accompanying drawings for detailed explanation.

[0031] like Figs. 1-5As shown, a large aperture 4K day and night confocal fisheye lens, the optical lens is composed of first lens, second lens, third lens, fourth lens, fifth lens, sixth lens, seventh lens, eighth lens and ninth lens arranged in order from object side to image side, and the diaphragm is arranged between the fifth lens and the sixth lens. The first lens, the second lens, the fourth lens and the ninth lens are glass spherical lenses, and the third lens, the fifth lens, the sixth lens, the seventh lens and the eighth lens are plastic aspherical lenses. Among them, the first lens, the second lens and the third lens are all arranged as negative meniscus lenses with negative focal length, which is conducive to adjusting the large-angle light, so that the large-angle light can enter the optical system as much as possible, and the light quantity of the system is increased; meanwhile, the first lens and the third lens are arranged as glass lenses, which can effectively reduce the damage of the external environment to the lens and avoid the deformation of the lens in harsh environment. The fourth lens is a lens with positive focal length, and the object side and the image side are both convex, which is conducive to converging the light passing through the front system and smoothly transitioning the light into the rear system. The fifth lens is a lens with negative focal length, and the object side is concave and the image side is convex. The diaphragm is arranged between the fifth lens and the sixth lens, which can balance the positive and negative focal lengths of the lens groups before and after the diaphragm, reduce the aberration of the optical system, and improve the imaging performance of the lens. The sixth lens is a plastic aspherical lens with positive focal length, and the image side and the object side are both convex. The seventh lens is a plastic aspherical lens with negative focal length, and the image side and the object side are both concave. The eighth lens is a plastic aspherical lens with positive focal length, and the image side and the object side are both convex. The ninth lens is a lens with positive focal length, and the object side and the image side are both convex. Through the reasonable collocation and arrangement of four glass spherical lenses and five plastic aspherical lenses, the optical system has good aberration correction ability and resolution ability, and can meet the requirements of 4K ultra-clear resolution, such as Figs. 2 to 5 As shown.

[0032] In the embodiment of the present application, the filter is selected from equivalent glass flat plates.

[0033] The technical indicators realized by the optical system of the embodiment are as follows:

[0034] (1) focal length: 1.0≤EFFL≤2.0mm;

[0035] (2) aperture F≤2.1;

[0036] (3) field of view angle: 2w≥187°;

[0037] (4) working waveband: visible light waveband and short-wave infrared waveband.

[0038] In order to realize the above design parameters, the specific design of the optical system of the embodiment is shown in the following table:

[0039]

[0040] The aspheric coefficients of each aspheric lens of the optical system of the embodiment are as follows:

[0041]

[0042] In the embodiment of the present application, the optical system has a large light aperture, low temperature drift and day and night focusing functions by reasonably allocating the optical power, surface shape of each lens, the center thickness of each lens and the axial distance between each lens, while meeting the needs of 4K ultra-high definition imaging of fisheye lens.

[0043] The present application is not limited to the above best embodiment, and anyone can derive other various forms of large aperture 4K day and night focusing fisheye lens under the inspiration of the present application. Any equivalent changes and modifications made within the scope of the patent application of the present application shall be covered by the present application.

Claims

1. A large aperture 4K day and night confocal fisheye lens, characterized in that: The optical system of the lens is composed of a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a diaphragm, a sixth lens, a seventh lens, an eighth lens and a ninth lens arranged in sequence along the optical axis from the object side to the image side; The first lens is a negative meniscus lens with negative focal power, the object side is convex, and the image side is concave; the second lens is a negative meniscus lens with negative focal power, the object side is convex, and the image side is concave; the third lens is a negative meniscus lens with negative focal power, the object side is convex, and the image side is concave; the fourth lens is a biconvex positive lens with positive focal power, both the object side and the image side are convex; the fifth lens is a lens with negative focal power, the object side is concave, and the image side is convex; the sixth lens is a biconvex positive lens with positive focal power, both the object side and the image side are convex; the seventh lens is a biconcave lens with negative focal power, both the object side and the image side are concave; the eighth lens is a biconvex positive lens with positive focal power, both the object side and the image side are convex; and the ninth lens is a biconvex positive lens with positive focal power, both the object side and the image side are convex; the first lens, the second lens, the fourth lens and the ninth lens are glass spherical lenses, and the third lens, the fifth lens, the sixth lens, the seventh lens and the eighth lens are plastic aspherical lenses; The focal length of the optical system is f, and the focal lengths of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens are f1, f2, f3, f4, f5, f6, f7, f8, f9 respectively, wherein f1, f2, f3, f4, f5, f6, f7, f8, f9 and f satisfy the following proportions: -10.0 The optical total length TTL of the optical system of the lens and the focal length f of the optical system satisfy: 16.0≤TTL / f≤18.0; The image height H of the optical system of the lens and the focal length f of the optical system satisfy: H / f≥3.

5. 2.The large aperture 4K day-night confocal fisheye lens according to claim 1, characterized in that: The first lens satisfies the relationship: 1.8 ≤ N d ≤ 2.0, V d ≥ 50.0; the second lens satisfies the relationship: 1.5 ≤ N d ≤ 1.8, V d ≥ 50.0; the third lens satisfies the relationship: 1.5 ≤ N d ≤ 1.8, V d ≥ 50.0; the fourth lens satisfies the relationship: 1.8 ≤ N d ≤ 2.0, V d ≤ 50.0; the fifth lens satisfies the relationship: 1.5 ≤ N d ≤ 1.8, V d ≤ 50.0; the sixth lens satisfies the relationship: 1.5 ≤ N d ≤ 1.8, V d ≥ 50.0; the seventh lens satisfies the relationship: 1.5 ≤ N d ≤ 1.8, V d ≤ 50.0; the eighth lens satisfies the relationship: 1.5 ≤ N d ≤ 1.8, V d ≥ 50.0; the ninth lens satisfies the relationship: 1.5 ≤ N d ≤ 1.8, V d ≥ 50.0; wherein N d is the refractive index, and V d is the Abbe number. 3.The large aperture 4K day-night confocal fisheye lens according to claim 1, characterized in that: The air gap between the first lens and the second lens is 3.5-4.0mm; the air gap between the second lens and the third lens is 1.0-2.0mm; the air gap between the third lens and the fourth lens is 2.0-3.0mm; the air gap between the fourth lens and the fifth lens is 0.5-1.0mm; the air gap between the fifth lens and the diaphragm is 0-0.1mm; the air gap between the diaphragm and the sixth lens is 0-0.5mm; the air gap between the sixth lens and the seventh lens is 0-0.5mm; the air gap between the seventh lens and the eighth lens is 0-0.5mm; and the air gap between the eighth lens and the ninth lens is 0-0.5mm.

4. The large aperture 4K day-night confocal fisheye lens according to claim 1, characterized in that: The third lens, the fifth lens, the sixth lens, the seventh lens and the eighth lens are aspherical lenses, and an aspherical curve equation expression is as follows: In the formula, z is the sagittal height of the aspherical surface at a position with a height of r along the optical axis from the vertex of the aspherical surface; c is the paraxial curvature of the aspherical surface; r = 1 / c; k is a conic constant; α1, α2, α3, α4, α5, α6, α7 and α8 are high-order coefficients.

5. The large-aperture 4K day and night confocal fisheye lens according to claim 1, characterized in that: The F number of the optical system of the lens is less than or equal to 2.

1.

6. The large-aperture 4K day and night confocal fisheye lens according to claim 1, characterized in that: The ninth lens is provided with a filter on the side of the negative image.

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